1. The Field of the Invention
The present invention relates to an arm assembly. In particular, although not exclusively, the invention relates to an arm assembly for an office chair where the armrest is adjustable for the comfort of the occupant. The invention also relates to a detachable arm assembly enabling the arm of a chair to be removed or substituted for another type e.g. a writing tablet. While the invention is described herein in terms of an office chair, it will be understood that the invention can be implemented in any type of chair including a wheelchair. Moreover, the invention might also have application beyond chairs. Arm assemblies of the invention may be attachable to a table or workstation, for example to be used as typists"" aids.
2. The Relevant Technology
Human beings come in all different shapes and sizes. For this reason, office chairs generally allow for adjustment e.g. seat height, seat depth. It is also known to provide for adjustment of armrests. A known adjustment includes a twisting action about a vertical axis. Another known type permits a twisting action as well as sideways movement. Another known type permits motion of the armrest in a predetermined oval path within a horizontal plane. Seat depth adjustment is one of the major adjustments required by an occupant of a chair and is to be commonly found on commercial office chairs. As the occupant adjusts their seat depth, the positioning of the armrests relative to the seat will vary even to the extent that the positioning of the armrests may be totally inappropriate for the occupant. Known office chairs do not satisfactorily meet the requirement of being easily adjustable to accommodate the seat depth position.
Another shortcoming of known armrest adjustment mechanisms is that they are not easy to adjust. In some known types, the user must reach under the armrest to effect the adjustment or alternatively use the opposite hand to make the adjustment. Adjustment in this fashion is awkward and cumbersome.
Yet another shortcoming of some of the known adjustable armrests is that they rely on force for adjustment. Therefore, while the occupant is using the chair in the normal fashion, the armrest will function as intended in the position selected by the user. However, if the user unintentionally bears considerable force against the armrests they can move. This often occurs when the occupant uses the armrests to lift himself out of the chair. This can be destabilising to the occupant and moreover, requires the occupant to re-adjust the armrests when he resumes occupancy of the chair.
It is therefore an object of the present invention to provide an armrest assembly which overcomes or at least addresses some of the foregoing disadvantages.
In accordance with a first aspect of the present invention there is provided an arm assembly for a chair wherein the chair has a forward direction and a rearward direction, said arm assembly comprising: an armrest; a support structure; a mounting device movably mounting the armrest to the support structure, wherein the mounting device constrains the movement of the armrest relative to the support structure to movement in a substantially horizontal plane having two degrees of freedom defined by first and second transversely arranged axes lying within the substantially horizontal plane to move in a substantially planar fashion without changing the orientation of the armrest.
It will be understood that the invention need not be limited to travel along the two pre-determined axes. It will be understood that the invention includes within its scope that the armrest is moveable along paths parallel to the first axis and additionally along paths parallel to the second axis. Thus the armrest may be permitted to move in a grid pattern. Additionally, the armrest is moveable in any direction along the substantially horizontal plane incorporating both the first and second axes. Suitably, the movement along the plane is within predetermined limits.
It is also preferred that the mounting device enables the armrest to adopt any one of a plurality of adoptable positions defined by the intersection of coordinate locations along the first and second axes. The term adoptable positions is thereby defined.
In a most preferred form of the invention, the first axis is generally aligned with the forward direction of the chair. Furthermore, the armrest might also be elongate in form with its longitudinal axis aligned with the forward direction of the chair. If the first axis is aligned with the forward direction of the chair then movement of the armrest along the second axis (or paths parallel thereto) will be in the sideways direction of the chair.
In accordance with a second aspect of the present invention there is provided an arm assembly for a chair having a forwards direction and a transverse direction, said arm assembly having a longitudinal axis such that the arm assembly is adapted to be assembled with the chair with the longitudinal axis of the arm assembly corresponding substantially to the forward direction of the chair, the arm assembly further having a transverse axis arranged such that with the arm assembly assembled with the chair, the transverse axis corresponds to the transverse direction of the chair; said arm assembly further comprising: an armrest; a support structure attachable to the chair, the armrest being mounted to the support structure by way of a mounting device such that the armrest is selectively moveable relative to the support structure forwards and backwards to adopt any one of a plurality of coordinate locations along the longitudinal axis and side to side to adopt any one of a plurality of coordinate locations along the transverse axis whereby the armrest is selectively positionable in any one of a plurality of adoptable positions defined by its respective coordinate locations along the longitudinal and transverse axes, the mounting device incorporating a locking device to releasably lock the armrest in any one of the adoptable positions.
The following discussion of optional features may be applicable to either of the first or second aspects of the invention set out above.
The invention may be further provided with guides to guide the movement along the first/longitudinal and second/transverse axes. The first guide may be provided on part of the mounting device, to guide movement of the armrest relative thereto with a corresponding first guided portion on the armrest. A second guide may be provided in fixed relationship to the support structure with a corresponding second guided portion provided on said part of the mounting device. In a preferred form of the invention, the first guide is provided on a carrier having the second guided portion for engagement with the second guide secured relative to the support structure to allow movement of the carrier relative to the support structure.
Preferably, the first guide is in the form of spaced tracks. Accordingly, there may be two corresponding first guided portions for engagement with the parallel spaced tracks. These may take the form of slots or channels provided on the armrest. Alternatively, the arrangement could be reversed with the first guide in the form of slots or channels with the first guided portions being in the form of one or more projections engageable in the slots or channels.
Similarly, the second guide may be in the form of a pair of parallel spaced opposed edges forming a part fixed relative to the support structure. The second guided portion may simply comprise the carrier being shaped for sliding engagement with the opposed edges.
Suitably, the length of the guides may determine the range of travel along the first and second axes. Stops may be provided to limit the range of travel along the first and second axes. As determined by the guides or by stops, the range of movement along the first axis may be larger than the range of movement along the second axis. For example, the range of movement in the forward/reverse direction may be greater than the range of movement permitted in the side to side direction.
The mounting device may enable the armrest to adopt any one of a finite number of adoptable positions. However, within the scope of the invention is the provision that there may be in infinite number of adoptable positions.
Where the mounting device enables the armrest to adopt any one of a plurality of adoptable positions defined by the intersection of coordinate locations of the first and second axes then it is preferred that there is a finite number of coordinate locations along the first and second axes with a resultant finite number of adoptable positions. This leads to a grid pattern of adoptable positions. With this in mind, there may be provided a fixed portion mounted in fixed disposition relative to at least the upper part of the support structure. This fixed portion could be part of the mounting device or alternatively an integral part of the support structure. The fixed portion may include a plurality of first engagement portions, there being a second engagement portion carried with the armrest for engagement with at least some of the first engagement portions. Alternatively, the plurality of first engagement portions may be carried with the armrest with the second engagement portion fixed relative to the support structure for engagement with at least some of the first engagement portions. In either case set out above, the arrangement of said some of the first engagement portions is such that each defines an adoptable position of the armrest when the second engagement portion is engaged therewith. In a preferred form of the invention, the arrangement of the first engagement portions may be in a grid pattern with the second engagement portion able to engage with at least some of the first engagement portions of the grid pattern.
The first and second engagement portions are shaped to enable engagement therebetween. Accordingly, in a preferred form of the invention, the second engagement portion may take the form of a discrete engagement member or an engagement projection. The first engagement members may be correspondingly shaped recesses/slots/holes to engagingly receive the engagement member or the engagement projection. In a most preferred form of the invention, the second engagement member is in the form of a ball and the first engagement members are in the form of dimples, shaped to receive the ball. In a most preferred form of the invention, the ball is carried by the armrest and the dimples are provided on the fixed portion fixed relative to the support structure. Accordingly, the fixed portion may include a dimple pad.
The recesses/slots/holes may have bevelled edges to enable the engagement members/engagement projections to be guided into position. Therefore, the ball and dimples arrangement is particularly preferred for the reason that the ball is easily locatable within any one of the dimples.
Where the second engagement portion is provided in the form of a discrete member e.g. ball, roller, the ball/roller may be normally biased into a position for engagement with one of the first engagement members.
Conversely, the first engagement portions may comprise discrete engagement members or engagement projections such as nodules. Additionally, the second engagement portion may be formed as a recess/slot/hole to receive one of the first engagement members or projections.
In another specific form of the invention, the first engagement members may be in the form of rollers with the second engagement portion being shaped as a trough-shaped recess to receive any one of at least some of the rollers.
In a preferred form of the invention, the plurality of first engagement portions are provided on the fixed portion. The fixed portion may extend forwardly or rearwardly of the carrier. Alternatively, the fixed portion may extend out partly forwardly and partly rearwardly of the carrier. This is the preferred form because in this way, the two sides of the fixed portion define opposing guides for the carrier. Some of the first engagement portions e.g. dimples, may also be provided on the carrier. This is particularly preferred where the carrier is centrally located. Therefore, there may be more than one second engagement portions. Preferably, there are two engagement portions e.g. two balls, with the arrangement of corresponding first engagement portions e.g. dimples, on the carrier being such that both second engagement portions are not engageable with the carrier at the same time. Where it is desirable to lock the armrest into position, this arrangement will preclude the armrest from being locked to the moveable carrier which is essentially a non-locking configuration of the armrest.
In a most preferred form of the invention, there are two balls carried by the armrest and two portions of the dimple pad are arranged forwardly and rearwardly respectively of a centrally disposed carrier with further dimples arranged on the carrier with three dimples extending across the width of the carrier wherein the spacing between the outermost dimples on the carrier is less than the spacing of the two balls such that with one of the balls engaging the carrier, the other ball engages with one or other of the portions of the dimple pad. The two balls could be discrete balls but alternatively could be joined.
In an alternative less preferred form of the invention, there may be one or more balls disposed on the fixed portion with the armrest carrying the dimple pad such that the dimple pad can engage with the balls and adopt any one of the plurality of adoptable positions.
It will be also appreciated that the invention is not limited to balls and a dimple pad. For example, the fixed portion may comprise one or more projections e.g. nodules. The arm portion may carry one or more dimple portions shaped for engagement with the nodules with the arrangement of nodules and dimples enabling the arm portion to adopt any one of the plurality of adoptable positions.
The armrest may be lockable in any one of the adoptable positions. In this regard, the armrest may be selectively lockable. However, it is preferred that the armrest is normally locked in each of the adoptable positions with a release device being provided to unlock the armrest from its adopted position. As such, the release device may release the engagement between the first and second engagement portions. The release device may be in the form of a separator to separate the second engagement portion out of engagement with the first engagement portion. Preferably, the separator is in the form of a moveable slide having an engagement position whereby the first and second engagement portions are in engagement and a release position allowing disengagement of the first and second engagement portions. Where the first engagement portions are in the form of a recesses and the second engagement portion comprises discrete engagement members then the moveable slide may include a shaped recess of graduated or varying depth with a shallow part and a deep part, with the engagement position of the slide corresponding to the discrete engagement member being received in the shallow part and the release position of the slide corresponding to the discrete engagement member being received in the deep part. The slide may be biased towards the engagement position.
In an alternative form of the invention where the first engagement portion comprises a plurality of projections e.g. nodules and the second engagement portion comprises a correspondingly shaped recess provided on the slide member, the slide may include an inclined surface opposite the recess which is in engagement with a ramped surface, whereby the slide is slidable along the ramped surface to allow the recess of the slide to lift out of engagement with the engaged nodule.
The release device may be directly operable by the user. Alternatively, the release device may incorporate an actuator. Preferably, the actuator is disposed for easy reach of the hand of a user whose corresponding arm is supported by the armrest.
The armrest may be elongate in shape to support a forearm of the chair occupant. A flat upper surface may be provided although a trough-shaped armrest is also possible. The preferred shape is convex both in X and Y planes. Preferably, the upper surface of the armrest is padded for comfort.
In accordance with yet another aspect of the present invention there is provided an arm assembly for a chair having a forwards direction and a transverse direction, said arm assembly having a longitudinal axis such that the arm assembly is adapted to be assembled with the chair with the longitudinal axis of the arm assembly corresponding substantially to the forward direction of the chair, the arm assembly further having a transverse axis arranged such that with the arm assembly assembled with the chair, the transverse axis corresponds to the transverse direction of the chair; said arm assembly further comprising: an armrest; a support structure attachable to the chair, the armrest being selectively moveable relative to the chair forwards and backwards to adopt any one of a plurality of coordinate locations along the longitudinal axis and side to side to adopt any one of a plurality of coordinate locations along the transverse axis whereby the armrest is selectively positionable in any one or a plurality of adoptable positions defined by its respective coordinate locations along the longitudinal and transverse axes; a locking device to releasably lock the armrest in any one of the adoptable positions wherein the locking device is operable by a user""s hand positioned on the armrest.
Any of the features discussed in connection with any of the foregoing aspects of the invention may be incorporated into the abovementioned aspect.
The armrest assembly according to any of the foregoing aspects of the invention may be incorporated into a chair. Suitably two armrests will be incorporated into each chair. Preferably, the chair is an office chair. The armrest may also be incorporated into a wheelchair or used as a typist""s aid at a workstation.
The chair and arm assembly may be designed such that the support structure is detachable from the chair. The support structure may comprise a column-like portion supporting the mounting device at its upper end. The column-like portion may include a height adjustment mechanism to enable the height of the armrest to be adjusted to suit the chair occupant. The lower end of the column-like portion may be connected to an attachment portion for detachable connection of the arm assembly to the chair.
In accordance with yet another aspect of the present invention there is provided a chair including: a main assembly having a seat portion, a back portion, and a support frame supporting the seat portion and the back portion; an arm assembly detachable from the main assembly, the arm assembly comprising: an armrest; a support structure having an upper end and a lower end, the support structure supporting the armrest at its upper end; and an elongate attachment portion disposed at or adjacent the lower end of the support structure, the elongate attachment portion having an external surface and including male engagement portions in defined areas of the external surface, the engagement portions including an outer male engagement surface and an inner male engagement surface spaced from each other; the main assembly further including an arm attachment portion in the form of a bore to receive the elongate attachment portion, the surface of the bore including female engagement portions in defined areas of the bore, the female engagement portions including an outer female engagement surface and an inner female engagement surface, the inner and outer female engagement surfaces being shaped and disposed such that upon insertion of the elongate attachment portion into the arm attachment portion, the outer male engagement surface and the inner male engagement surface are caused to releasably engage with the inner female engagement surface and the outer female engagement surface respectively wherein the male engagement surfaces are formed on portions of the elongate attachment portion which are non-tapering and of small length in comparison to the length of the elongate attachment portion.
In a preferred form of the invention, the elongate attachment portion is downwardly inclined relative to the support structure. In this way, any downward force applied to the armrest will be resolved in the elongate attachment portion in a manner tending to push the elongate attachment portion into the arm attachment portion of the main assembly. A force in the upright direction applied to the armrest will also resolve in the elongate attachment portion in the same manner due a cantilever effect.
The arm attachment portion which includes the female engagement surfaces may be disposed on any part of the chair such as the seat portion or a lower region of the back portion. In a most preferred form of the invention the arm attachment portion is disposed on the support frame. The support frame may include a main transom supported by a pneumatic spring. It is desirable that the arm attachment portion is defined at one end of the main transom.
Preferably, the length of the mutual engagement between the outer male engagement surface and the inner female engagement surface is less than 5 mm. Likewise, it is preferred that the length of the mutual engagement of the inner male engagement surface and the outer female engagement surface is less than 5 mm.
Preferably, the portions of the elongate attachment portion including the male engagement surfaces are of uniform cross-section. The cross-sections of the mutually engaging engagement surfaces should naturally correspond. The outer male engagement surface may be provided at the end of the elongate attachment portion but not necessarily so. An intermediate portion is defined between the outer male engagement surface and the inner male engagement surface. This may be of any shape including tapering, provided that it does not interfere with the insertion of the elongate attachment portion into the arm attachment portion.
The arm attachment portion could be a hollow member. However in a more preferred form of the invention, the arm attachment portion comprises first and second bands incorporated into the transom.
A clip may also be provided to prevent inadvertent detachment of the arm assembly from the main assembly. Preferably, the clip is normally locked with an actuator provided to disengage the clip and release the elongate attachment portion from the main assembly attachment portion.
In accordance with a further aspect of the invention there is provided an armrest for a chair, wherein the armrest incorporates a guide and slide member slidably mounted thereto, the slide member accommodating an optical disc which provides operating instructions for the chair, the slide member being moveable along the guide between a retracted position and an extended position in which an occupant of the chair can access the optical disc.
Preferably, the slide member is manually operable by the user. Preferably, the slide is moveable from the retracted position fully received within the armrest, to an extended position forward of the armrest, the slide member extending through a forward opening in the armrest.
This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more of said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.
The invention consists in the foregoing and also envisages constructions of which the following gives examples.